Contrast reinforcement for displays

ABSTRACT

The invention relates to a method and a device for contrast enhancement for display devices. A high-contrast representation of optical signals and/or symbols is achieved by providing a light-absorbing and/or light-deflecting background which is dark in comparison to the symbol or signal to be displayed and thus highlights said symbol or signal. The following invention enables a high-contrast representation of optical signals and symbols by the provision of a dark, light-absorbing background.

The invention relates to a method and a device for contrast enhancementfor display devices. A high-contrast representation of optical signalsand/or symbols is achieved by providing a light-absorbing and/orlight-deflecting background which is dark in comparison to the symbol orsignal to be displayed and thus highlights said symbol or signal. Thefollowing invention enables a high-contrast representation of opticalsignals and symbols by the provision of a dark, light-absorbingbackground.

BACKGROUND OF THE INVENTION

Optical displays are often hard to view in bright surroundings. For thepurpose of counteracting this and heightening the contrast between thedisplay and the surroundings, the light efficiency of the means must beincreased which entails that more energy is consumed. Anotherpossibility consists in the provision of shielding elements which areintended to shield the display from extraneous light incident on it. Asa rule, such shielding means restrict the viewability of the display orshield it only insufficiently from incident extraneous light, such as,e.g., sunlight. Shielding the display from variable extraneous light,e.g. with a moving incident angle, often turns out to be difficult.

DE-T-693 26 611 discloses a device for preventing a false lightphenomenon in a signal lamp, said device being provided between a lightsource and a cover lens and comprising a pair of complex sphericallenses in a specific arrangement and a shielding element positionedbetween said pair of lenses and having light-transmitting holes.

SUMMARY OF THE INVENTION

The present invention is therefore based on the object of providing amethod and a device with which the contrast between display or signaland background or surroundings is heightened irrespective of thedirection and the intensity of the incident extraneous light. A furtherobject to be achieved with the present invention resides in overcomingfurther disadvantages of the prior art.

These objects are achieved with the features of the claims. Theinvention is based on the inventive concept that light incident on thedevice from the outside is directed through a lens to a means thatabsorbs and/or deflects the light so that a dark background is created.The brightness of said background is in contrast to the respectivesignal and/or symbol so that the latter can be clearly seen by theviewer. Furthermore, the light efficiency required for the clearvisibility of the signal or symbol is reduced so that energy is saved.

In a preferred embodiment of the invention, the device comprises atleast one converging lens, at least one apertured diaphragm as well asat least one means for absorbing light. The device further optionallycomprises a light source. The converging lens, the apertured diaphragmand the absorption means are arranged in the mentioned order, the lenscollecting the incident light and guiding it through the aperture to theabsorption means. The absorption means exhibits preferably alight-absorbing preferably dark or black layer.

In a further preferred embodiment, the device comprises at least oneconverging lens, at least one apertured diaphragm as well as at leastone means for deflecting or reflecting light. Furthermore, theembodiment optionally comprises a light source. As in theabove-described preferred embodiment, the incident light is collected bythe lens and directed through the aperture to the means for deflectinglight.

A further preferred embodiment according to the invention consists inthe combination of the two aforementioned embodiments, wherein the meansarranged behind the diaphragm—relative to the direction of incidence ofthe light—is designed as a means for deflecting and absorbing light.

A further preferred embodiment of the invention comprises at least onedivergent lens as well as at least one means for deflecting and/orabsorbing light. In a further preferred embodiment, this device furthercomprises at least one light source.

In a further particularly preferred embodiment of the invention, thedevice comprises at least one light source in addition to the describedfeatures. In this connection, the device comprises preferably activeand/or passive light sources. Active light sources are preferablyconfigured as laser, incandescent lamp, light-emitting diode (LED),organic LED (OLED), electroluminescent foil (EL foil), neon tube, etc.Passive light sources, e.g., light valves or optical waveguidestypically consist of a reflecting layer which reflects incident light.For this purpose, preferably the light incident on the device, alsoreferred to as extraneous light, is utilized. In a particularlypreferred embodiment, the reflecting layer is replaced with a liquidcrystal display.

In a further preferred embodiment, the light of the light source istransmitted to the intended place via optical waveguides. In a furtherpreferred embodiment, the device comprises light sources of differentprimary colours (e.g. RGB) so that in case of large-scale indication,for instance, various secondary colours can be represented with highcontrast. In a further preferred embodiment, at least three lightsources are provided for the three primary colours which jointly use onelens each.

The light source is preferably arranged in a further plane that is infront of, in or behind the lens. When the light source is positionedbehind the lens, it is simultaneously used for focussing the emittedlight. In further preferred embodiments, the light source can bearbitrarily positioned. In this connection, it is possible to use thedevice for generating a dark, preferably contrastive area.

In a further preferred embodiment, the light sources in their turn areprovided with optical means. These means are preferably convex orconcave lenses, mirrors and/or reflection elements, etc. When light orextraneous light is incident on the device, it is focussed in the lensand directed through the aperture to the means for deflecting orabsorbing light. In said means, the light is deflected and/or absorbed,with the way back through the diaphragm being more or less blocked. Thisentails a significant contrast improvement, i.e., the display area isrelatively dark even in bright surroundings or with direct insolation.When the light source is activated, a clearly visible light source withhigh contrast is the result.

In a preferred embodiment, the angle of radiation is determined via theposition of the light source, which is arranged in front of, within,behind and/or beside the lens. In a further preferred embodiment, theangle of radiation is determined via the position of the light sourcerelative to the focus of the lens. In a further preferred embodiment ofthe invention, the possible angle of incidence of the light to beabsorbed is adjusted by the size of the aperture and/or the distancebetween lens and aperture/diaphragm. It is furthermore preferred thatthe preferential direction of the light or of the extraneous light to beabsorbed, such as, e.g., sunlight, is adjusted by the position of theaperture. The contrast improvement is preferentially also adjustable bythe size of the aperture.

Furthermore, the aperture is preferably variably adjustable as regardsits size and position so that direct stray light, such as, e.g., sunrays or floodlight, etc., can be deflected into the area between theaperture and the means for deflecting and/or absorbing light or to saidmeans. In a further preferred embodiment of the invention, the diaphragmhas several apertures per lens.

In a further preferred embodiment, the means for absorbing or deflectinglight comprises at least one area which reflects and/or absorbs thelight directed to said means. This area is preferably large relative tothe area of the lens in order to further heighten the contrast.Preferably, for greater extraneous light incidence, the described areais to be configured larger relative to the area of the lens.Furthermore, an enlargement of the area is preferably to be achieved byroughening it, inclining it relative to the incident light, structuringit by means of, e.g., an undulated surface, configuring a pyramid-likestructure, etc.

In a further preferred embodiment, the means is realized as a cavityarranged directly behind the aperture. Preferably, said cavity has aninner surface that is suitable to absorb the incident light. This innersurface is preferably dark, black and/or coated. Preferably, the innersurface exhibits a layer of graphite and/or roughened graphite.Furthermore, the cavity and/or the inner walls of the means is/arepreferably suitable to absorb light. The cavity has preferably acylindrical, conical, spherical and/or cuboid configuration.

In a further preferred embodiment of the invention, the means and/or thecavity of the means comprise(s) further cavities and the area in frontof and/or behind the aperture and/or the area behind the lenscomprise(s) a preferably translucent material and/or fluid or is/arefilled with it. The preferably translucent material and/or the fluidpreferably comprise(s) a different refractive behaviour in comparison tothe lens. The translucent material is preferably plastics. The fluid ispreferably a gas and preferentially an inert gas.

In a further preferred embodiment of the invention, the device comprisesonly one lens or only lenses which is/are preferably arranged in frontof and/or outside of the means for absorbing or deflecting light.

The described structure is preferably designed as an injection-mouldedpart with inserted glass or plastics lens and/or glass or plasticsmirror.

In a preferred embodiment of the invention, all optical (translucent)parts are provided with an antireflective coating in order to furtherheighten the contrast. Preferably, the structure is to be realized blackand/or considerably roughened to minimize reflections. In a furtherpreferred embodiment, the device comprises at least one shieldprotecting it against extraneous light or sunlight incident under toosteep an angle. The shield is preferably arranged at least partly aroundthe lens.

In a further preferred embodiment, the light source itself is realizedas a lens and/or an array of lenses (e.g. LED) and passes the incidentlight on as described above. In a preferred embodiment, the diaphragm isrealized as a liquid crystal display. In the embodiment as a liquidcrystal display, the size and/or position of the diaphragm and/or theaperture is/are preferably adjustable.

In a particularly preferred embodiment, the device and/or display of thedevice consist of several lenses and/or several light sources. A devicesystem or array preferably consists of cuboid lenses without a distanceand/or elongate lenses comprising a slit diaphragm.

In a preferred embodiment according to the invention, the arrangement isflat, cubical, cylindrical and/or a segment of a circle, etc., in orderto, i.a., increase the angle of reflection.

In a preferred embodiment, when arranging devices of the invention in anarray, the illuminated area can be selectively determined by a differentposition of the light sources relative to the focus of the associatedlens. This entails, for instance, that, e.g., traffic lights are alsoviewable from directly below.

In a further preferred embodiment, when arranging the light sourcesasymmetrically relative to the focus of the lens, the area illuminatedby the light source is adjustable.

In a further preferred embodiment, the contrast can be even furtherheightened by the use of several lenses and/or by reflection with theaid of mirrors and/or by enlarging the area of the means for absorbingand/or deflecting light.

In a further embodiment of the invention, the angle of incidence of theextraneous light can be determined with the aid of sensors so that thesize of the diaphragm and/or its position can be adjusted accordingly.In a further preferred embodiment, the light efficiency of the lightsource can be reduced when there is no or little extraneous light orwhen a high contrast has been achieved.

Further preferred embodiments of the invention are realized innanotechnology in order to manufacture small displays appropriate fordaylight.

DESCRIPTION OF THE DRAWINGS

The invention is explained in the following by means of preferredembodiments and the drawings in which

FIG. 1 shows a schematic representation of a first preferred embodimentof the invention,

FIG. 2 shows a schematic representation of a second preferred embodimentof the invention,

FIG. 3 shows a schematic representation of a third preferred embodimentof the invention,

FIG. 4 shows a schematic representation of a fourth preferred embodimentof the invention,

FIG. 5 shows a schematic representation of a fifth preferred embodimentof the invention,

FIG. 6 shows a schematic representation of a sixth preferred embodimentof the invention,

FIG. 7 shows a schematic representation of a seventh preferredembodiment of the invention,

FIG. 8 shows a schematic representation of an eighth preferredembodiment of the invention,

FIG. 9 shows a schematic representation of a ninth preferred embodimentof the invention, and

FIG. 10 shows a schematic representation of a tenth preferred embodimentof the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a preferred embodiment of a device according to theinvention comprising a lens 1, a diaphragm 2 as well as a means 3 fordeflecting and/or absorbing light. The lens 1, the diaphragm 2 and themeans 3 are arranged such that light 5 incident from the outside isfocussed by the lens 1 and directed through the aperture 6 to the means3. The incident light 5 impinges on the means 3 at the area 7. In apreferred embodiment, the area 7 has light-absorbing properties so thatit reflects only a small proportion of the light 5. For this purpose,the area 7 is preferably at least partially dark or black and/orexhibits a coating having absorbing properties. Graphite or roughenedgraphite, for example, belongs to this type of coating.

In a further preferred embodiment of the invention, the means 3 forms acavity 8 extending behind the diaphragm 2. The inner surfaces of thecavity 8 exhibit preferably absorbing properties. This is preferablyachieved by the preferred embodiments described in connection with thearea 7. Light coming into the cavity 8 through the aperture 6 is thuspartly absorbed and partly reflected at the inner surfaces of the means3. Preferably, the light is reflected to a slight extent only, if atall. Reflected light in turn impinges onto another area of the innersurface of the means 3, where it is again absorbed and reflected to aslight extent only. This process recurs until the incident light hasbeen absorbed completely or at least almost completely. Preferably,approximately 50% to 99.9999% of the incident light are absorbed. Sincethe aperture 6 of the diaphragm 2 is small relative to the inner surfaceof the means 3 and since the means 3 absorbs the incident light 5, nolight comes back from the means 3 through the aperture 6. Since the lens1 focuses all light coming through it through the aperture 6 to themeans 3, where it is absorbed, the background of the lens 1, i.e., thefront side of the diaphragm 2, remains dark since no light impinges ontothe diaphragm 2. The dark area thus stands out contrastingly against thesurroundings illuminated by the incident light 5. When a light source ora signal is positioned in the vicinity of the means 3, the means 3 ishighlighted to a greater extent on account of the contrast to the darkarea of the device and thus more clearly visible. Preferably, a contrastgain of approximately 50% to 99.9999% can be achieved with an embodimentaccording to the invention. The ratio of the area of the aperture 6 tothe area of the light impinging onto the lens 1 is preferably 1:2 to1:10,000 and particularly preferably 1:4 to 1:1,000.

In a further preferred embodiment, the means 3 is configured integrallywith the diaphragm 2 and/or the housing of the device.

In a further preferred embodiment, the means for absorbing and/ordeflecting light comprises reflecting elements and/or surfaces, such as,e.g., mirrors, etc. They reflect the incident light 5 such that itcannot get back through the diaphragm 2 and direct it to a place whereit can be returned to the surroundings and/or absorbed (not shown).

In a further preferred embodiment of the invention, an additional mediumis arranged in the means and/or in the cavity 8 of the means. In aparticular embodiment of the invention this medium is preferably atranslucent material and/or a fluid at least partially filling the meansand/or the cavity 8. The medium has preferably a different refractivebehaviour in comparison to the lens 1. In a preferred embodiment of theinvention, the medium has properties by means of which thecontrast-enhancing properties of the means 3 are supported or furthered.

In a preferred embodiment of the invention, the medium is a translucentmaterial, preferably plastics. In a further preferred embodiment of theinvention, the fluid is a gas, preferably an inert gas.

In further preferred embodiments, the area in front of and/or behind thediaphragm 2 and/or the area behind the lens 1 at least partlycomprise(s) a medium of the above-described type. Preferably, furtherhollows and cavities required by the design may also comprise a mediumof the described type. In a further preferred embodiment of theinvention, the cavity 8 and/or the aforementioned areas are completefilled by a medium and/or replaced with it.

In a further or additional preferred embodiment of the invention, thedevice comprises only one lens 1 or only lenses 1 which is/arepreferably arranged in the direction of light incidence in front of thediaphragm 2 and/or in the direction of light incidence in front of oroutside the means 3 for absorbing or deflecting light. Preferably, themeans 3 for absorbing or deflecting light does not comprise a lens 1.

In a particularly preferred embodiment, the device comprises at leastone light source 4, as shown in FIG. 2. In the illustrated example, thelight source 4 is arranged directly adjacent to the aperture 6. Thelight emitted by the light source 4 is converted by the lens 1 into asubstantially parallel beam which is indicated in the Figure by thebroken line 9. The light source 4 is preferably an active or passivelight source. In a preferred embodiment according to the invention, bothactive and passive light sources, e.g., light valves or opticalwaveguides, are used. As active light sources 4, preferably lasers,incandescent lamps, light-emitting diodes (LEDs), electroluminescentfoils (EL foils), neon tubes and/or organic LEDs (OLEDs), etc. are used.Passive light sources, e.g., light valves or optical waveguides 4 usethe incident light, which they preferably reflect. For this purpose, thelight sources 4 preferably comprise a reflective surface or layer. In aparticularly preferred embodiment, the light source 4 is a liquidcrystal display.

In a further preferred embodiment, the light source 4 is an area or issheet-like and has an aperture in the size of a diaphragm or larger.This light source 4 is preferably realized as an OLED and/or comprises afluorescing material or lamp(s).

The at least one light source 4 can alternatively be also arranged infront of, in and/or beside the lens 1. In the particularly preferredembodiments, the lens 1 is used to scatter the light 9 emitted by thelight source 4.

In a further preferred embodiment of the invention, the light of atleast one light source 4 is directed by means of at least one opticalwaveguide to a preferred place, preferably adjacent to the aperture 6.In further preferred embodiments of the invention, at least one lightsource 4 comprises further optical means, such as, e.g., lenses ormirrors. In a further preferred embodiment, the light sources 4 emitlight of different colours. In a further preferred embodiment, thedevice comprises three light sources for each lens 4, each of whichemits light of one of the three primary colours. Preferably, the threelight sources 4 emit light of a different primary colour each.

According to a further or an additional embodiment of the invention, thedevice comprises a light source 4 in the direction of light incidencebehind (in the drawing to the right of) the diaphragm 2 or in the means3 for deflecting and/or absorbing the light, the cavity 8 and/or thearea 7 (not shown). This light source 4 is preferably realized as anactive light source 4 and particularly preferably as a laser or diode,wherein the light emitted by the light source reaches the outside in adirected or focussed manner through the aperture 6 and is preferablydiverged or scattered by the lens 1. In this connection, the lightsource 4 is preferably configured or arranged such that it essentiallydoes not influence the deflecting and/or absorbing properties of themeans 3.

In a further preferred embodiment, the device comprises at least oneshield 10, which is arranged in the vicinity of the lens 1 and protectsthe device or the lens 1 against light incidence from unfavourableangles of incidence.

FIG. 3 shows a preferred embodiment according to the invention, whereinthe device comprises an arrangement of three devices as those describedin connection with FIG. 1 and/or FIG. 2. The devices are preferablyarranged beside each other and/or on top of each other. A large numberof these devices may form a two-dimensional array.

In a particularly preferred embodiment according to the invention,several devices comprising a lens 1, a diaphragm 2, a means 3 having anarea 7 and a light source 4 are arranged such that the lenses 1, thediaphragms 2 and the areas 7 are in one plane each.

FIG. 4 shows a particularly preferred embodiment of a device accordingto the invention, which comprises three lenses 1, one diaphragm 2 havingthree apertures 6 as well as one means 3 with an area 7. The individualfeatures are preferably realized as described in connection with theabove Figures. In particular, it is also possible that a plurality oflenses 1 and apertures 6 are provided, which are arranged, for instance,as a two-dimensional array.

The preferred embodiments described in FIGS. 3 and 4 preferably compriseelements having the same or equivalent features and/or properties. In afurther preferred embodiment, the individual elements, such as, e.g.,the lenses 1, the diaphragms 2, the apertures 6 or the means 3 havedifferent features and/or properties. In a further preferred embodimentof the invention, the distance between lens 1 and diaphragm 2 isvariably adjustable by means of the lens 1 and/or the diaphragm 2. In afurther preferred embodiment, the position and/or size of the aperture 6is/are variably adjustable. The device can preferably be adjustedaccording to the expected and/or given operating conditions by means ofsuch adjusting possibilities. In a further preferred embodiment, thedevice comprises sensors which determine the angle of incidence and/orthe intensity of the extraneous light 5, whereupon the diaphragm 2, thesize of the aperture 6, the position of the aperture 6 and/or thedistance between lens 1 and diaphragm 2 is/are adjusted or adjustableaccordingly.

In a further preferred embodiment, the lens 1 is preferably square,rectangular, round or oval. When a device according to the inventioncomprises several lenses 1, said lenses 1 preferably have the same ordifferent shapes and features.

In a further preferred embodiment, the aperture 6 is round, oval or aslit. In a preferred embodiment, elongate lenses 1 are used incombination with slit diaphragms 2.

FIG. 5 shows a preferred embodiment according to the invention, whereinthe light source 4 or the light sources 4 itself/themselves is/are alens/lenses 1. The light source(s) 4 or the lens(es) 1 directs/directthe incident light through the aperture(s) 6 to the (one or more) means3 and emits/emit its/their own light 9. The combination of light source4 and lens 1 as shown in FIG. 5 is preferably also used in connectionwith the other preferred embodiments of the invention.

In a further preferred embodiment, the light efficiency of the lightsource 4 is variably adjustable.

The focussing, emission, reflection and/or absorption of the device issupported by the preferred arrangement of the mirror element orelements. Furthermore, all optical and/or translucent elements of thedevice, such as, e.g., the lens 1 and/or the light source 4, areprovided with an antireflective coating in order to prevent, forexample, i.a. a reflection of the incident light 5 at the outer surfaceof the lens 1. In a further preferred embodiment, the non-opticalelements of the device, such as, e.g., the diaphragm 2, the shield 10and/or housing parts exhibit absorbing properties, for instance by adark or black colour and/or a roughened surface. These elements arepreferably coated with graphite and/or roughened graphite.

In a further preferred embodiment of the invention, the diaphragm 2 is aliquid crystal display.

FIG. 6 shows a preferred embodiment of the invention, wherein the devicecomprises several lenses 1, diaphragms 2 and light elements 4 as well asone or more means 3. They are arranged concentrically relative to eachother as rings such that the lenses 1 have an extent of up to 360° inthe circumference around the diaphragms 2 and the (one or more) means 3.Such an arrangement is preferably circular and/or polygonal. In furtherpreferred embodiments, the device and/or an array of devices is flat,cubical, cylindrical and/or a segment of a circle, etc. Preferably,i.a., the angle of reflection thus can be increased.

FIG. 7 shows a preferred embodiment of the invention in which the means3 exhibits an area 7 and/or inner surface of the cavity 8 which is/aremodified in its/their form and/or is/are enlarged. In the shown example,the cavity 8 has a funnel-shaped expansion. Preferably, the area 7and/or the inner surface of the cavity 8 of the means 3 is/areroughened, undulated, inclined relative to the incident light and/orpyramid-like structured, etc. Furthermore, the cavity 8 of the means ispreferably cylindrical, conical, spherical and/or cuboid.

In a further preferred embodiment of the invention, the light source 4is a liquid crystal display illuminated by the extraneous light.

FIG. 8 shows a further preferred embodiment of the invention, in which alight-scattering means that is preferably realized as a divergent lens12 and thus replaces the diaphragm 2 is used instead of the lens 1. Inthe shown example, the device comprises a divergent lens 12 with concavesurfaces as well as a means 3 with an area 7. The light coming throughthe divergent lens 12 is scattered, i.e. the light beam is diverged anddirected to the preferably light-absorbing area 7. Preferred embodimentscorrespond to the above described ones.

In a further preferred embodiment of the invention, the device comprisesat least one mirror and/or at least one mirror section. The mirrorand/or mirror section is/are preferably at least partially curved and/orbent. FIG. 9 shows an example with a curved first mirror 14, whichpreferably is a paraboloidal-type reflector. In this example, anaperture 15 is provided approximately in the middle of the first mirror.A second mirror 16 is arranged at a distance relative to the directionof the incident light in front of the mirror 14. In the example, saidsecond mirror 16 is a flat reflective area. The light 5 impinging ontothe first mirror 14 is reflected to the second mirror 16 and directed bysaid second mirror to the aperture 15 in said first mirror. Thearrangement and/or shape of the mirrors is/are selected such that theimpinging light falls through the aperture 15 and impinges onto the area7 arranged behind the aperture 15. The light is absorbed as describedabove in connection with the other examples. FIG. 10 shows analternative embodiment in which a scattering mirror 18 is arranged inthe cavity 8. The light 5 falling into the cavity is reflected at thescattering mirror 18 being configured as a convex mirror and is directedto the light-absorbing area 7.

In a preferred embodiment of the invention, the described design ormeans 3 can be manufactured as an injection-moulded part. The lens 1 aswell as the mirror 14, 16, 18 are preferably configured as glass orplastics lenses and/or as mirrors. In a further preferred embodiment,they can be placed or inserted into the means 3 formed as aninjection-moulded part.

Devices and methods according to the invention are preferably used inthe field of traffic influence, such as, e.g., in connection withtraffic lights, danger signs, signs giving directions, prohibitingsigns, traffic guidance systems, etc.

In a further preferred embodiment, the device is realized innanotechnology in order to manufacture small displays appropriate fordaylight. Further devices according to the invention are used as a smalldisplay in the field of electronic devices, such as, e.g., calculators,radios, telephones, etc.

The technological background as well as the use and the field ofapplication of the devices according to the invention show that they arepreferably not restricted in terms of dimension but, depending on thecase of application, may considerably differ in configuration, shapeand/or dimension.

As regards their configurations, the individual features of theabove-described preferred embodiments can be combined in any way infurther preferred embodiments.

The device according to the invention has the advantage that thecontrast of a display device or a signal device between display symboland background is heightened so that the display or the signal can bemore distinctly and clearly viewed by a viewer and/or the user. Thisproves to be practicable above all in applications at daylight oragainst the light. Furthermore, the device according to the inventionenables the saving of energy since the light sources require less powerdue to the heightened contrast. In some preferred embodiments, noelectrical power is required at all.

1. A device for contrast enhancement for display devices, comprising afocusing optical device including a lens for focusing incident light, adiaphragm with at least one aperture arranged, relative to the incidentlight, behind the lens, a light disposal element for absorbing lightarranged, relative to the incident light, behind the diaphragm, whereinthe optical device is arranged such that it focuses incident light anddirects it through the at least one aperture to the light disposalelement for absorbing extra light, and at least one light sourcearranged between the focusing optical device and the diaphragm, whereina lens is used for focusing the emitted light from the light source, thelight source supplying illumination of a display element viewable by aviewer and wherein at least one light source is arranged beside the lensused for focusing the emitted light.
 2. The device according to claim 1,wherein the light disposal element comprises an absorbing cavityarranged, relative to the incident light, behind the diaphragm.
 3. Thedevice according to claim 2, wherein the device comprises severaldiaphragms arranged adjacent to each other directing light to pluralapertures.
 4. The device according to claim 3, wherein the diaphragmsand/or the apertures have different sizes.
 5. The device according toclaim 4, wherein the size of at least one of said apertures isadjustable.
 6. The device of claim 3 comprising plural focusing opticaldevices, wherein the focusing optical devices correspond in number tosaid several diaphragms and are arranged in a regular pattern.
 7. Thedevice according to claim 1, wherein said focusing optical device is anelongate lens and wherein said diaphragm is a slit diaphragm.
 8. Thedevice according to claim 1, wherein the focusing optical device isseparated from the diaphragm by an adjustable distance.
 9. The deviceaccording to claim 1, wherein said light source is adjacent saiddiaphragm.
 10. The device according to claim 9, wherein said lightsource passively reflects light.
 11. The device according to claim 1,wherein the diaphragm is a liquid crystal element.
 12. The deviceaccording to claim 9, wherein the light source is in the form of astructure that is sheet-like and has an opening, wherein the size of theopening is at least equal to the size of the diaphragm aperture.
 13. Thedevice according to claim 1, wherein the light disposal element absorbsextraneous light, the angle of incidence of the extraneous light beingdetermined with the aid of sensors to facilitate adjustment of theposition of the diaphragm, the size of the aperture and/or its position.14. A method for contrast enhancement for display devices, comprisingfocusing an optical device including a lens for focusing incident light,providing a diaphragm with at least one aperture arranged, relative tothe incident light, behind the lens, absorbing light using a lightdisposal element arranged, relative to the incident light, behind thediaphragm, wherein the optical device is arranged such that it focusesincident light and directs it through the at least one aperture to thelight disposal element for absorbing extra light, and arranging at leastone light source between the focusing optical device and the diaphragm,providing a lens for focusing the emitted light from the light source,the light source supplying illumination of a display element viewable bya viewer, and wherein at least one light source is arranged beside thelens used for focusing the emitted light.